My wife and I have just returned from a short break at Hotel Dreisonnenberg. We were greeted at the door by Manuel - I don't think I've ever received a handshake from the management when I've checked into a hotel before!
As other's have said, the hotel is spotlessly clean and very, very quiet. We had one of the few rooms with double beds. It was a little strange though that the bed came equipped with two single duvets.
If I were being picky, I'd say that the pillows were a bit on the useless side.
The hotel provided a plentiful breakfast and we had three evening meals there too. The food was all to a very good standard.
I've seen other reviews of the hotel complain about the wifi. We had no problem at all, except that it is a little slow. Given the location of the hotel, it is entirely understandable.
The bottom line is that I would not have any hesitation about staying there again if I were ever to visit the area for a second time.